Ross and Neufeld Microbiome (2015) 3:66 DOI 10.1186/s40168-015-0135-0 RESEARCH Open Access Microbial biogeography of a university campus Ashley A. Ross and Josh D. Neufeld* Abstract Background: Microorganisms are distributed on surfaces within homes, workplaces, and schools, with the potential to impacthumanhealthanddisease.Universitycampusesrepresent a unique opportunity to explore the distribution of microorganisms within built environments because of high human population densities, throughput, and variable building usage. For example, the main campus of the University of Waterloo spans four square kilometres, hosts over 40,000 individuals daily, and is comprised of a variety of buildings, including lecture halls, gyms, restaurants, residences, and a daycare. Results: Representative left and right entrance door handles from each of the 65 buildings at the University of Waterloo were swabbed at three time points during an academic term in order to determine if microbial community assemblages coincided with building usage and whether these communities are stable temporally. Across all door handles, the dominant phyla were Proteobacteria, Firmicutes, Actinobacteria,andBacteroidetes, which comprised 89.0 % of all reads. A total of 713 genera were observed, 16 of which constituted a minimum of 1 % of the 2,458,094 classified and rarefied reads. Archaea were found in low abundance (~0.03 %) but were present on 42.8 % of the door handles on 96 % of buildings across all time points, indicating that they are ubiquitous at very low levels on door handle surfaces. Although inter-handle variability was high, several individual building entrances harbored distinct microbial communities that were consistent over time. The presence of visible environmental debris on a subset of handles was associated with distinct microbial communities (beta diversity), increased richness (alpha diversity), and higher biomass (adenosine 5′-triphosphate; ATP). Conclusions: This study demonstrates highly variable microbial communities associated with frequently contacted door handles on a university campus. Nonetheless, the data also revealed several building-specific and temporally stable bacterial and archaeal community patterns, with a potential impact of accumulated debris, a possible result of low human throughput, on detected microbial communities. Keywords: University campus, Door handles, Microbiome, Human skin, High-throughput sequencing, Built environment, Outdoor microbiology, Biofilm Background approaches, the microbiome of each region of the human Antonie van Leeuwenhoek first discovered organisms body can now be explored thoroughly. living on surfaces linked to the human body in the seven- Skin is the largest organ of the body and is comprised teenth century using simple microscopes [1]. For the next of a diverse range of mostly harmless and beneficial three centuries, studies of human-associated microorgan- organisms [3]. The skin microbiota varies between body isms focused on the diversity, morphology, and metabol- sites and individuals, exhibiting greater collective diver- ism of a limited group of cultured isolates. Organisms that sity than both the human oral cavity and gut [4]. In a were initially cultured from healthy skin in the 1950s survey of skin microbiota, Propionibacteria, Corynebac- include Staphylococcus epidermidis, Micrococcus,andPro- teria, and Staphylococcus spp. comprised over 62 % of pionibacterium [2]. With the advent of modern molecular sequences detected across 20 body sites [5]. Corynebacteria spp. associated with moist skin, Propionibacteria and Staphylococcus spp. dominated sebaceous areas, and both * Correspondence: [email protected] Betaproteobacteria and Flavobacteriales were abundant in Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada dry regions. Using 3D molecular cartography maps and a © 2015 Ross and Neufeld. Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Ross and Neufeld Microbiome (2015) 3:66 Page 2 of 12 survey of skin microbiota across ~400 human skin sites, a within a room can be detected through airborne microor- recent study demonstrated that Actinobacteria, Firmicutes, ganisms and settled particles within 1.5–4 h after entering Proteobacteria, Cyanobacteria,andBacteroidetes were the [15]. These results reinforce the importance of occupants most common phyla detected [6]. Previous research dem- in shaping microbial communities associated with build- onstrated that the majority of the human skin microbiota ing surfaces [16]. are temporally stable [4], yet hand microbial communities University campuses are unique built environments with are dynamic and possess a larger proportion of transient high population densities and throughput, in addition to organisms [7, 8]. Despite the majority of these organisms being represented by buildings with distinct uses. For being benign or beneficial for health, transient and oppor- example, the University of Waterloo is comprised of 65 tunistic pathogens are present that can cause several com- buildings within four square kilometers. The main campus mon human diseases. For example, Staphylococcus aureus, has almost 40,000 full-time students and 4000 staff and Corynebacterium minutissimum,andPseudomonas aerugi- faculty. Campus buildings are widely varied in their usage, nosa are the respective causes of atopic dermatitis, ery- including lecture halls, gyms, health and optometry clinics, thrasma, and green nail syndrome [9]. dormitories, a day care, and restaurants. A common fea- Human skin is of interest for the study of the built ture of these buildings is their entranceways. Most campus environment because, in addition to possessing its own buildings have metal door handles that are touched by microbial community, skin commonly represents the many students each day, presumably exchanging a portion first point of contact between humans and microbes. In of their personal skin microbiota with contacted surfaces. contrast to previous generations, inhabitants of industri- Thepublichealthimportanceoftheseuniversity-based alized countries spend the majority of their time indoors built environment interactions is highlighted by previous [10], in daily contact with a variety of surfaces at home, work demonstrating that pathogenic bacteria can survive work, and when traveling. Studies that examine human- on metal surfaces for extended periods of time, even weeks associated built environments are important for better [17]. Exacerbating the numerous colds and flus that are understanding the microbes that humans encounter transmitted in dormitories and lecture halls, some univer- frequently, which has implications for health and dis- sity students may not be diligent hand washers. In an obser- ease. Indeed, recent studies focusing on the built envir- vationalstudyatalargepublicuniversityinTexas,over onment found that public restroom surfaces host diverse 25 % of university students did not wash their hands after microbial communities that are primarily composed of each bathroom use [18]. Of students that washed their human-associated organisms [11]. This suggests that hands, 58 % used soap and only 26 % employed an microorganisms on skin are deposited during short pe- adequate hand washing technique. Inadequate personal riods of contact. This is further supported by the finding hygiene can increase the diversity of microorganisms on that microorganisms deposited on computer keyboards hands and, by extension, on contacted surfaces [8]. Of par- resemble those from the hands that typed on them [12], ticular interest is the finding that hand washing practices which has potential forensic implications. varied greatly within a university based on the designated Surface-associated bacterial communities exhibit sea- use of the building that a student occupies [18]. Specifically, sonal variation, although differences in building use have a students were more likely to wash their hands in the bath- larger impact on the community than the time of the year room of an academic building than in a recreation center. [13]. Homes were found to contain a variety of communi- The main objective of this study was to determine if ties whose composition was impacted directly by the university campus buildings host distinct microbial com- usage of the surfaces that were swabbed. Surfaces that munities on door handle surfaces that reflect building were cleaned frequently had a lower diversity than un- usage. An additional objective was to evaluate whether washed surfaces [14]. In addition, homes with dogs had door handle surfaces were temporally stable throughout higher bacterial diversity and relative abundance of dog- an academic term. We show that although door handle associated bacteria on the majority of surfaces. Interest- communities were highly variable overall, microbial com- ingly, the microbial community on kitchen surfaces in the munity profiles can be unique to several buildings and, in home